JP2021129042A - Semiconductor devices and their manufacturing methods - Google Patents

Abstract

To provide a semiconductor device capable of improving performance of a block insulation film, and a method for manufacturing the same.SOLUTION: According to one embodiment, a semiconductor device comprises a laminated film alternately including a plurality of electrode layers and a plurality of insulation layers. The semiconductor device also comprises a first insulation film, a charge storage layer, a second insulation film, and a semiconductor layer provided in this order in the laminated film. The device further comprises a third insulation film provided between the electrode layers and the insulation layers and between the electrode layers and the first insulation film, and including an aluminum oxide film of an α crystal phase in the laminated film.SELECTED DRAWING: Figure 5

Description

An embodiment of the present invention relates to a semiconductor device and a method for manufacturing the same.

The block insulating film of the three-dimensional memory is formed so as to include, for example, a metal insulating film such as an aluminum oxide film in addition to the silicon oxide film. In order to improve the performance of the block insulating film, it is desired to form a block insulating film containing a suitable metal insulating film.

Japanese Unexamined Patent Publication No. 2009-132961 JP-A-2009-55030

Karl Wefers and Chanakya Misra, Alcoa Technical Paper, No.19, Revised (1987) Alcoa Laboratories

Provided are a semiconductor device capable of improving the performance of a block insulating film and a method for manufacturing the same.

According to one embodiment, the semiconductor device includes a laminated film including a plurality of electrode layers and a plurality of insulating layers alternately. The device further includes a first insulating film, a charge storage layer, a second insulating film, and a semiconductor layer, which are sequentially provided in the laminated film. The device is further provided between the electrode layer and the insulating layer and between the electrode layer and the first insulating film in the laminated film, and includes an aluminum oxide film having an α crystal phase. 3 Insulating film is provided.

It is a perspective view which shows the structure of the semiconductor device of 1st Embodiment. It is sectional drawing (1/4) which shows the manufacturing method of the semiconductor device of 1st Embodiment. It is sectional drawing (2/4) which shows the manufacturing method of the semiconductor device of 1st Embodiment. It is sectional drawing (3/4) which shows the manufacturing method of the semiconductor device of 1st Embodiment. It is sectional drawing (4/4) which shows the manufacturing method of the semiconductor device of 1st Embodiment. It is sectional drawing which shows the detail of the manufacturing method of the semiconductor device of 1st Embodiment. It is a graph for demonstrating the characteristic of the semiconductor device of 1st Embodiment. It is a graph for demonstrating the characteristic of the insulating film 5b, 5c of 1st Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIGS. 1 to 8, the same configurations are designated by the same reference numerals, and redundant description will be omitted.

(First Embodiment)
FIG. 1 is a perspective view showing the structure of the semiconductor device of the first embodiment. The semiconductor device of FIG. 1 is, for example, a three-dimensional NAND memory.

The semiconductor device of FIG. 1 includes a core insulating film 1, a channel semiconductor layer 2, a tunnel insulating film 3, a charge storage layer 4, a block insulating film 5, and an electrode layer 6. The block insulating film 5 includes an insulating film 5a and an insulating film 5b. The electrode layer 6 includes a barrier metal layer 6a and an electrode material layer 6b. The insulating film 5a in the block insulating film 5 is an example of the first insulating film, the tunnel insulating film 3 is an example of the second insulating film, and the insulating film 5b in the block insulating film 5 is an example of the third insulating film. be.

In FIG. 1, a plurality of electrode layers and a plurality of insulating layers are alternately laminated on a substrate, and a memory hole H1 is provided in these electrode layers and the insulating layer. FIG. 1 shows one of these electrode layers, the electrode layer 6. These electrode layers function, for example, as word lines of NAND memory. FIG. 1 shows the X and Y directions parallel to the surface of the substrate and perpendicular to each other, and the Z direction perpendicular to the surface of the substrate. In the present specification, the + Z direction is treated as an upward direction, and the −Z direction is treated as a downward direction. The −Z direction may or may not coincide with the direction of gravity.

The core insulating film 1, the channel semiconductor layer 2, the tunnel insulating film 3, the charge storage layer 4, and the insulating film 5a are formed in the memory hole H1 and form a memory cell of the NAND memory. The insulating film 5a is formed on the surfaces of the electrode layer and the insulating layer in the memory hole H1, and the charge storage layer 4 is formed on the surface of the insulating film 5a. The charge storage layer 4 is capable of accumulating charges between the outer side surface and the inner side surface. The tunnel insulating film 3 is formed on the surface of the charge storage layer 4, and the channel semiconductor layer 2 is formed on the surface of the tunnel insulating film 3. The channel semiconductor layer 2 functions as a channel of a memory cell. The core insulating film 1 is formed in the channel semiconductor layer 2.

The insulating film 5a is, for example, a SiO ₂ film (silicon oxide film). The charge storage layer 4 is, for example, a SiN film (silicon nitride film). The tunnel insulating film 3 is, for example, a laminated film including a SiON film (silicon oxynitride film) and a SiO _{2 film.} The channel semiconductor layer 2 is, for example, a polysilicon layer. The core insulating film 1 is, for example, a SiO ₂ film.

The insulating film 5b, the barrier metal layer 6a, and the electrode material layer 6b are formed between insulating layers adjacent to each other, and include a lower surface of the upper insulating layer, an upper surface of the lower insulating layer, and a side surface of the insulating film 5a. It is formed in order. The insulating film 5b is, for example, a metal insulating film such as an _{Al 2} O _{3 film (aluminum oxide film).} The barrier metal layer 6a is, for example, a TiN film (titanium nitride film). The electrode material layer 6b is, for example, a W (tungsten) layer.

Further details of the insulating film 5b of the present embodiment will be described below.

The insulating film 5b is, for example, an Al ₂ O ₃ film having an α crystal phase. _{the Al} 2 _{O 3} film of α crystal phase has a typical _Al 2 _{O 3 the Al} 2 _{O 3} film of film in a γ crystal phase equivalent dielectric constant. On the other hand, the barrier height for Si (silicon) layer of the _Al 2 _{O 3} film of α crystalline phase, 0.7 eV is higher than the barrier height to Si layer of the _Al 2 _{O 3} film of γ crystalline phase. The barrier height difference of 0.7 eV is effective in reducing the back tunneling current from the word line during the erasing operation of the NAND memory. Therefore, according to the present embodiment, it is possible to reduce the leakage current of the NAND memory by forming _{the Al 2} O ₃ film of the α crystal phase as the insulating film 5b.

_{The Al 2} O ₃ film of the γ crystal phase has a semi-stable structure called a defective spinel structure, whereas the Al ₂ O ₃ film of the α crystal phase has the most stable structure called a corundum structure. Have. In the Al ₂ O ₃ film of the ^{γ crystal phase, the O 2-} ions form a face-centered cubic lattice, and the Al ³⁺ ions are 6- or 4-coordinated. On the other hand, in the Al ₂ O ₃ film of the α crystal phase, the O ^2- ions form a hexagonal close-packed structure, and the Al ³⁺ ions regularly occupy 2/3 of the 6-coordination sites. Because of these differences between the Al ₂ O ₃ film of γ crystal phase of the Al ₂ O ₃ film and the α-crystal phase, or the Al ₂ O ₃ film is in a or α crystal phase in γ crystalline phase Can be identified by X-ray diffraction.

2 to 5 are cross-sectional views showing a method of manufacturing the semiconductor device of the first embodiment.

First, the base layer 12 is formed on the substrate 11, and a plurality of sacrificial layers 13 and a plurality of insulating layers 14 are alternately formed on the base layer 12 (FIG. 2). As a result, a laminated film 15 including a plurality of sacrificial layers 13 and a plurality of insulating layers 14 alternately is formed on the base layer 12. Next, the memory hole H1 penetrating the laminated film 15 and the base layer 12 is formed (FIG. 2). As a result, the upper surface of the substrate 11 is exposed in the memory hole H1.

The substrate 11 is, for example, a semiconductor substrate such as a Si substrate. The base layer 12 is, for example, a laminated film including a lower insulating film 12a, a semiconductor layer 12b, and an upper insulating film 12c which are sequentially provided on the substrate 11. The lower insulating film 12a is, for example, a SiO ₂ film or a _{laminated film including a SiO 2} film and another insulating film. The semiconductor layer 12b is, for example, a polysilicon layer. The upper insulating film 12c is, for example, a SiO ₂ film or a _{laminated film including a SiO 2} film and another insulating film. The sacrificial layer 13 is, for example, a SiN film, and the insulating layer 14 is, for example, a SiO ₂ film. The sacrificial layer 13 is an example of the first membrane. The memory hole H1 may be formed so as to reach the semiconductor layer above the substrate 11 instead of being formed so as to reach the substrate 11.

Next, the insulating film 5a, the charge storage layer 4, and the tunnel insulating film 3 are formed in this order on the surfaces of the substrate 11, the base layer 12, and the laminated film 15 in the memory hole H1 (FIG. 3). Next, the insulating film 5a, the charge storage layer 4, and the tunnel insulating film 3 are removed from the bottom of the memory hole H1 by etching (FIG. 3). As a result, the upper surface of the substrate 11 is exposed again in the memory hole H1. Next, the channel semiconductor layer 2 and the core insulating film 1 are sequentially formed on the surfaces of the substrate 11 and the tunnel insulating film 3 in the memory hole H1 (FIG. 3). As a result, the insulating film 5a, the charge storage layer 4, the tunnel insulating film 3, the channel semiconductor layer 2, and the core insulating film 1 are sequentially formed on the side surfaces of the base layer 12 and the laminated film 15 in the memory hole H1.

Next, a slit (not shown) is formed in the laminated film 15, and the sacrificial layer 13 is removed with a chemical solution such as phosphoric acid using this slit. As a result, a plurality of cavities H2 are formed between the insulating layers 14 (FIG. 4). These cavities H2 are examples of recesses.

Next, the insulating film 5b, the barrier metal layer 6a, and the electrode material layer 6b are formed in this order on the surfaces of the insulating layer 14 and the insulating film 5a in the cavity H2 (FIG. 5). As a result, the block insulating film 5 including the insulating film 5a and the insulating film 5b is formed. Further, an electrode layer 6 including a barrier metal layer 6a and an electrode material layer 6b is formed in each cavity H2, and a plurality of electrode layers 6 and a plurality of insulating layers 14 are alternately included on the base layer 12. The laminated film 16 is formed.

In each cavity H2, an insulating film 5b, a barrier metal layer 6a, and an electrode material layer 6b are formed between the upper insulating layer 14 and the lower insulating layer 14. Therefore, the insulating film 5b in each cavity H2 is formed on the lower surface of the upper insulating layer 14, the upper surface of the lower insulating layer 14, and the side surface of the insulating film 5a, and the upper insulating layer 14 and the lower insulating layer are formed. It is sandwiched between the 14 and the insulating film 5a and the barrier metal layer 6a. As described above, the insulating film 5b of the present embodiment is, for example, an Al ₂ O ₃ film having an α crystal phase. Details of the method for forming the insulating film 5b will be described later.

In this way, the semiconductor device of the present embodiment is manufactured (FIG. 5). FIG. 1 shows a part of the semiconductor device shown in FIG.

FIG. 6 is a cross-sectional view showing details of the method for manufacturing the semiconductor device of the first embodiment. 6 (a) to 6 (c) show the details of the step of forming the insulating film 5b in FIG.

First, the insulating film 5c is formed on the surfaces of the insulating layer 14 and the insulating film 5a in the cavity H2 (FIG. 6A). The insulating film 5c is, for example, an aluminum compound film different from _{the Al 2} O _{3 film.} An example of such an insulating film 5c is an AlN film (aluminum nitride film) which is an amorphous phase aluminum compound film. The insulating film 5c is an example of the second film. Note that FIG. 6A shows an insulating film 3a (for example, a SiO ₂ film) and an insulating film 3b (for example, a SiON film) included in the tunnel insulating film 3.

The insulating film 5c (AlN film) of the present embodiment is formed by ALD (Atomic Layer Deposition) in a vertical decompression batch furnace. Specifically, the insulating film 5c is formed at a temperature of 300 to 400 ° C. using _{TMA (trimethylaluminum, Al (CH 3} ) _{3 ) as a raw material gas and ammonia (NH 3} ) as a nitriding agent. Will be done. The film thickness of the insulating film 5c is controlled by adjusting the number of ALD cycles. In the present embodiment, as described later, the AlN film of the amorphous phase in the Al ₂ O ₃ film of α-crystal phase by changing the thermal oxidation, changing the insulating film 5c on the insulating film 5b. According to this thermal oxidation, the insulating film 5c is oxidized and crystallized at the same time, and the insulating film 5c is changed to the insulating film 5b.

The insulating film 5c may be another aluminum compound film. An example of such an insulating film 5c is an aluminum compound film having an amorphous phase containing an aluminum (Al) element and a nitrogen (N) element. For example, an AlON film (aluminum oxynitride film) and an AlCN film (aluminum carbonitriding). Membrane), AlCON film (aluminum carbonated film) and the like. The insulating film 5c may be any other insulating film as long as it is formed as an aluminum compound film other than the crystalline phase and oxidation and crystallization proceed at the same time by thermal oxidation. Further, although the insulating film 5c is formed by using TMA which is a liquefied gas in the present embodiment, it may be formed by sublimating a solid material such as _{AlCl 3 (aluminum chloride).}

Next, the insulating film 5c is thermally oxidized (FIG. 6 (b)). As a result, oxidation and crystallization of the insulating film 5c proceed at the same time, and the insulating film 5c (amorphous phase AlN film) changes to the insulating film 5b (α crystal phase Al ₂ O ₃ film) (FIG. 6 (c)). ..

In the present embodiment, heat application and oxidation are simultaneously performed by radical oxidation to change the insulating film 5c into an insulating film 5b. For example, an insulating film 5c having a film thickness of 2.3 to 2.5 nm is subjected to radical oxidation for 10 to 30 seconds at a temperature of 930 to 1050 ° C. and a pressure of 10.5 torr. At this time, O radicals and OH radicals are generated by simultaneously supplying _{H 2} gas and O _{2 (oxygen) gas so that the partial pressure ratio of H 2} (hydrogen) gas is 2 to 20%, and O Radicals oxidize the insulating film 5c (see FIG. 6B). As a result, the insulating film 5c expands, and an insulating film 5b having a film thickness of about 3 nm can be obtained. In this embodiment, O radicals are generated by heat, but plasma may be used instead to generate O radicals.

When the insulating film 5c is changed to the insulating film 5b by radical oxidation, the silicon (Si) element and oxygen (Si) element and oxygen (Si) element and oxygen (Si) between _{the insulating film 5a (SiO 2 film) and the charge storage layer 4 (SiN film) due to the influence of the radical.} A layer L containing an element O) and an element nitrogen (N) is formed (see FIG. 6 (b)). The layer L is a layer of an oxide film containing a nitrogen element, and is formed so as to extend in the Z direction sideways (X direction in FIG. 6B) of the plurality of cavities H2 and the plurality of insulating layers 14. The layer L has a thickness of, for example, 0.8 to 1.0 nm, and remains in the finally completed semiconductor device. Layer L is an example of the first layer. As will be described later, the nitrogen concentration in the layer L of the present embodiment is higher than the nitrogen concentration in the charge storage layer 4.

The thermal oxidation of the insulating film 5c may be carried out by hydroxylation instead of radical oxidation. For example, an insulating film 5c having a film thickness of 2.3 to 2.5 nm is hydroxylated for 10 to 60 minutes at _{a temperature of 850 to 950 ° C. and a partial pressure of H 2 O (water) of 384 torr in a vertical decompression batch furnace.} I do. At this time, steam purified using a water generator is introduced into the furnace as water for hydroxylation. As a result, the insulating film 5c expands, and an insulating film 5b having a film thickness of about 3 nm can be obtained. The process of hydroxylating the insulating film 5c is an _{atmospheric pressure process in which water vapor is diluted with N 2} (nitrogen) gas, but a decompression process may be used instead.

After executing the steps of FIGS. 6 (a) to 6 (c), the barrier metal layer 6a and the electrode material layer 6b are sequentially formed in the cavity H2 via the insulating film 5b (see FIG. 5). .. In this way, the semiconductor device of the present embodiment is manufactured.

FIG. 7 is a graph for explaining the characteristics of the semiconductor device of the first embodiment.

Curve C1 represents the result of XRR (X-ray reflectivity) measurement on the charge storage layer 4, the insulating film 5a, and the insulating film 5b before performing the radical oxidation of FIG. 6B. Curve C2 represents the result of XRR measurement on the charge storage layer 4, the insulating film 5a, and the insulating film 5c after performing the radical oxidation of FIG. 6 (b). The horizontal axis of FIG. 7 represents the X coordinate shown in FIG. 6B and the like, and the vertical axis of FIG. 7 represents the intensity measured by the XRR measurement.

As shown in FIG. 7, the curve C2 shows a peak between the charge storage layer 4 and the insulating film 5a. This indicates that a layer L containing nitrogen atoms at a high concentration was formed between the charge storage layer 4 and the insulating film 5a. According to the result of the XRR measurement, it was found that the nitrogen concentration in the layer L was higher than the nitrogen concentration in the charge storage layer 4.

FIG. 8 is a graph for explaining the characteristics of the insulating films 5b and 5c of the first embodiment.

FIG. 8 shows the relationship between the crystal structure _{of the Al 2} O _{3 film and the temperature.} For example, the arrow P1 indicates that an Al ₂ O ₃ film having a γ crystal phase can be formed at 780 ° C. or lower. Further, the arrow P2 indicates that an Al ₂ O ₃ film having an α crystal phase can be formed at about 1100 ° C. Further, the arrow P3 indicates that an Al ₂ O ₃ film having an α crystal phase can be formed at about 800 to 1400 ° C.

Here, the aluminum oxide film in an amorphous phase (AlO _X layer), heated by assuming a case of changing the aluminum oxide film of the crystalline phase (Al ₂ O ₃ film). In this case, increasing the temperature range of 500 to 1000 ° C. The temperature of the AlO _X film from room temperature, AlO _X film, not only may change _{the Al} 2 _{O 3} film of α-crystal phase as indicated by the arrow P3 , There is a possibility that it changes to _{an Al 2} O ₃ film of the γ crystal phase as shown by the arrow P1. In the latter case, if raising the temperature of the AlO _X layer from room temperature to about 1100 ° C., AlO _X layer changes in _{the Al} 2 _{O 3} film of γ crystalline phase (arrow P1), _Al 2 O subsequent to γ crystalline phase _{The three films will change to Al 2} O ₃ films in the α crystal phase (arrow P2). However, in this case, alpha crystalline phase and may require a high temperature heating of the Al ₂ O ₃ film about 1100 ° C. to effect the, gamma Al crystalline phase of the Al ₂ O ₃ film affected by alpha crystalline phase _{There is a problem that the 2} O ₃ film is less likely to be formed.

Therefore, in this embodiment, the amorphous phase of the aluminum nitride film (AlN film) by thermal oxidation is changed into aluminum oxide film of the crystalline phase (Al ₂ O ₃ film). Accordingly, the AlN film of the amorphous phase is maintained at least up to 780 ° C., it becomes possible to change the AlN film in an amorphous phase in the Al ₂ O ₃ film of the crystalline phase at a temperature higher than 780 ° C.. In this case, since passing through the temperature zone of temperature already arrow P1 of the AlN film, AlN film, without passing through the state of the _Al 2 _{O 3} film of γ crystalline phases, alpha crystalline phase of the _Al 2 _{O 3} film Will change to. That, AlN film, without nucleation of γ crystalline phase is carried out, it will change in the Al ₂ O ₃ film of α crystal phase. _{Therefore, according to the present embodiment, the Al 2} O ₃ film (insulating film 5b) of the α crystal phase is formed without heating at a high temperature of about 1100 ° C. (arrow P3), and the Al _{2 of the γ crystal phase is formed. O 3 Al} 2 O ₃ film of α-crystal phase under the influence of the membrane to prevent the (insulating film 5b) is less likely to occur (arrow P2) becomes possible.

As described above, the block insulating film 5 of the present embodiment includes an α crystal phase Al ₂ O ₃ film as the insulating film 5b. Therefore, according to the present embodiment, the performance of the block insulating film 5 can be improved by _{the Al 2} O _{3 film of the α crystal phase.}

For example, _{the Al} 2 _{O 3} film of α crystalline phase, like _{the Al} 2 _{O 3} film of γ crystalline phase, has a high dielectric constant. Therefore, according to the present embodiment, _{by using the Al 2} O ₃ film of the α crystal phase, it is possible to realize the block insulating film 5 having high performance as in the case of using _{the Al 2} O ₃ film of the γ crystal phase. It will be possible.

Further, the barrier height with respect to Si layer of the _Al 2 _{O 3} film of α crystalline phase, 0.7 eV is higher than the barrier height to Si layer of the _Al 2 _{O 3} film of γ crystalline phase. Therefore, according to the present embodiment, _{by using the Al 2} O ₃ film of the α crystal phase, it is possible to further reduce the leakage current as compared with the case of using _{the Al 2} O ₃ film of the γ crystal phase.

Further, according to this embodiment, by forming an Al ₂ O ₃ film of α-crystal phase from the dense AlN film from AlO _X film, it is possible to form a less insulating film 5b e.g. defects.

Although some embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel devices and methods described herein can be implemented in a variety of other forms. In addition, various omissions, substitutions, and changes can be made to the forms of the apparatus and method described in the present specification without departing from the gist of the invention. The appended claims and their equivalent scope are intended to include such forms and variations contained within the scope and gist of the invention.

1: Core insulating film 2: Channel semiconductor layer 3: Tunnel insulating film,
3a, 3b: Insulating film, 4: Charge storage layer, 5: Block insulating film,
5a, 5b, 5c: Insulating film, 6: Electrode layer, 6a: Barrier metal layer, 6b: Electrode material layer,
11: Substrate, 12: Underlayer, 12a: Lower insulating film, 12b: Semiconductor layer,
12c: Upper insulating film, 13: Sacrificial layer, 14: Insulating layer, 15, 16: Laminated film

Claims (12)

A laminated film containing a plurality of electrode layers and a plurality of insulating layers alternately,
A first insulating film, a charge storage layer, a second insulating film, and a semiconductor layer, which are sequentially provided in the laminated film,
In the laminated film, a third insulating film provided between the electrode layer and the insulating layer and between the electrode layer and the first insulating film and containing an aluminum oxide film having an α crystal phase, and a third insulating film.
A semiconductor device equipped with. The semiconductor device according to claim 1, wherein the first insulating film contains a silicon element and an oxygen element. The semiconductor device according to claim 1 or 2, further comprising a first layer containing a silicon element, an oxygen element, and a nitrogen element between the first insulating film and the charge storage layer. The semiconductor device according to claim 3, wherein the first layer is provided on the side of the plurality of electrode layers and the plurality of insulating layers. The charge storage layer contains a silicon element and a nitrogen element, and contains
The semiconductor device according to claim 3 or 4, wherein the nitrogen concentration in the first layer is higher than the nitrogen concentration in the charge storage layer. A laminated film containing a plurality of first films and a plurality of insulating layers alternately is formed.
A first insulating film, a charge storage layer, a second insulating film, and a semiconductor layer are formed in this laminated film in this order.
The first film is removed to form a plurality of recesses between the insulating layers.
A plurality of third insulating films including an aluminum oxide film having an α crystal phase and a plurality of electrode layers are sequentially formed in the recesses.
A method of manufacturing a semiconductor device including the above. The third insulating film is
A second film containing an aluminum compound film is formed in the recess.
The second film is changed to the third insulating film.
The method for manufacturing a semiconductor device according to claim 6, which is formed by the above. The method for manufacturing a semiconductor device according to claim 7, wherein the second film changes to the third insulating film by thermal oxidation. The method for manufacturing a semiconductor device according to claim 7 or 8, wherein the second film includes the aluminum compound film having an amorphous phase. 9. When the second film changes to the third insulating film, the aluminum compound film changes to the aluminum oxide film of the α crystal phase without going through the state of the aluminum oxide film of the γ crystal phase. The method for manufacturing a semiconductor device according to. The method for manufacturing a semiconductor device according to any one of claims 7 to 10, wherein the aluminum compound film contains an aluminum element and a nitrogen element. The method for manufacturing a semiconductor device according to claim 11, wherein the aluminum compound film includes an aluminum nitride film, an aluminum oxynitride film, an aluminum carbon nitride film, or an aluminum carbonate nitride film.

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